Midrasz do Wyjścia 13:6

3) "the festival of matzoth to the L–rd, seven days, etc." What is the intent of this? Because it is written (Devarim 16:8) "Six days shall you eat matzoth and on the seventh day it is a cessation (atzereth) for the L–rd" — The seventh day was included in the general (mitzvah of matzoh, viz.: [Shemoth 13:6] "Seven days shall you eat matzoth; and it left that general category to serve as a paradigm, viz.: Just as (the eating of matzoth on) the seventh day is permitted (and not obligatory), so, all (of the days) are permitted (in this regard, and not obligatory.) I might think that (the eating of matzoth on) the first night, too, is permitted (and not obligatory); it is, therefore, written (Devarim 16:3) "Upon it shall you eat matzoth" — Scripture makes it mandatory.

Rabbi José said: Haman was an astrologer, and he wrote letters on slips, and cast lots by the constellations to know the distinction between one day and another, and between one month and another, and between one constellation and another, as it is said, "They cast Pur, that is, the lot, before Haman from day to day, and from month to month" (Esth. 3:7). He wrote and sent throughout all the provinces to destroy and to slay and to exterminate all the Jews on the thirteenth day of the month Adar, on the third day in the constellation Leo. Mordecai heard (thereof), and rent his garments, and put on sackcloth with ashes, and he went forth into the midst of the city, as it is said, "And Mordecai knew all that was done" (Esth. 4:1); and he cried before the Holy One, blessed be He, saying: Sovereign of all the worlds ! Thou didst swear to our fore-fathers to multiply their seed like the stars of the heaven, and now hast Thou given them like sheep to the slaughter. "Remember Abraham, Isaac, and Israel… to whom thou swarest… I will multiply your seed as the stars of heaven" (Ex. 32:13). Esther heard (thereof), and her strength failed, as it is said, "And the queen was exceedingly enfeebled" (Esth. 4:4). She sent and called for Hathach, the trusty (servant) of her household, to know what had been done to Mordecai. Hathach went forth to Mordecai, who told him the words. (Hathach) went in and told Esther. Haman saw Hathach coming and returning, and he slew him, and Esther did not find another man faithful enough to send to Mordecai. She said that it was her || desire to return answer to Mordecai. She said to him, "Go, gather together all the Jews that are present in Shushan, and fast ye for me, and neither eat nor drink three days" (Esth. 4:16). These (days) were the thirteenth, the fourteenth, and the fifteenth of Nisan. Mordecai said to her: Is not the third day (of the fast) the day of Passover? She said to him: Thou art the elder in Israel. If there be no Israel, wherefore is the Passover? Mordecai hearkened to her words, and he agreed with her. "So Mordecai transgressed" (Esth. 4:17). What is the meaning of the expression, "So he transgressed"? That he transgressed the festivals and Sabbaths. On the third day (of the fast) Esther put on the royal apparel, and sent and invited the king and Haman to the banquet which she had prepared on the fifteenth of Nisan. When they had eaten and drunk, Haman said: The king exalts me, and his wife aggrandizes me, and there is none greater than I am in all the kingdoms; and Haman rejoiced very much in his heart, as it is said, "Then went Haman forth that day, joyful and glad of heart" (Esth. 5:9).

R. Shimon b. Elazar says: One verse states "Six days shall you eat matzoth," and another, (Shemoth 13:6) "Seven days shall you eat matzoth!" — Six of the new grain (after the omer offering on the second day); seven of the old grain.